Certain platinum compounds have been shown to be potent antitumor drugs against a number of animal and human tumors. Recently, a new class of compounds called platinum blues - because of their blue color -have been brought to light. Of these "platinum uracil blue" (Pt)NH3)2Uracil) and "platinum thymine blue" (Pt(NH3)2Thymine) show binding with isolated bovine thymus DNA precipitating it into fine blue fibrils. These compounds show superior activity against the ascites Sarcoma-180 tumor in Swiss white mice when compared to cis-dichlorodiammine platinum (II) (NSC 1119875). Activity is also shown against Rauscher leukemia, Ehrlich ascites and ADJ/PC6A tumors. Again "platinum-uracil blue" complex causes only minor focal damage to the proximal convoluted tubules at a therapeutic dose level, rather than the generalized kidney toxicity so prominent with NSC 119875. Platinum compounds are suspected of exposing the antigen sites or enhancing the antigenicity by binding with the antigens on the infected cell surfaces. "platinum-uracil blue" complex and "platinum thymine blue" show specific binding to nucleic acids or structures containing nucleic acids. Further, recent studies indicate that platinum blue compounds show specific binding on the surface of tumor cells (ascites sarcoma-180, myeloma MOPC-21, KB line, and rat embryonic cells RESI). Such experiments when performed on non-transformed cells (chick fibroblasts, mouse liver, bovine testis, kidney cells, mouse embryonic skin, human fibroblasts) no such binding is observed. From the number of cells tested it is believed that only the tumorigenic cells show any binding at the surface. Main aims of the proposed study now are to develop specific methods for use of these compounds as E.M. stains for nucleic acids - because of their specific binding and to develop methods to identify the tumor cells under the electron microscope - because of platinum binding to surface. Fresh frozen thin sections of the tumor tissue would be best for such studies. BIBLIOGRAPHIC REFERENCE: Aggarwal, S.K. 1975. Surface binding of platinum-pyrimidine complexes and the nucleic acids in the solid human tumors. J. Cell Biol. 67, 3a.